How to know what EVC system I have?

Not sure if you're still looking for this information but I've just gone down this road and will share what I found. I have a 2010 3350 with the 8.1 engines. What I found is that the motors were actually produced in 2007 even though the boat is newer. You can call your local dealer with your engine serial # (on a sticker on the engine cover) and they will tell you the year of your engines. I say this because if you start looking at documentation thinking that your engine year will be the same as your boat model year, that may not be the case. 

If you open your dash up and look at your tachometers, this will likely tell you what you need to know. Specifically, if they do not have a 6 pin connector on the tachs, you don't have EVC (Electronic Vessel Control) - sorry. That said, there is still a way to do what you want. The installation instructions for the Volvo Easy Connect setup is helpful to determine what you have.

Easy Connect Installation Instructions

If you take a look at the top of your engines, there will be a gray 6 or 8 pin. My engines had the 8 pin connections



So for me, I needed the Volvo Penta adapter cables to go from 8 pin to 6 pin configuration and an Easy Connect module for each engine. 

I ended up going with a different company that offers an engine gateway for the Volvo Penta engines. They are a bit cheaper and the adapter cables are way cheaper which in the end saved me a few hundred dollars over going with Volvo parts. The company is Yacht Devices U.S.

So essentially, I needed 2 Engine Gateways, two adapter harnesses, a 30 ft NEMA 2000 cable and some T's, a terminator, etc. This got me connected to my Garmin GPSMap 3310XSV chart plotter and it all works fantastic. Hopefully this information will help someone else out there as the information is not the easiest to find.